Brake knockback is a phenomenon that can occur when a vehicle is driven through an aggressive turn, is engaged in aggressive maneuvers, or is otherwise driven in an environment where significant lateral forces are exerted on the vehicle's wheels. This can cause an angular deflection of the rotor, which in turn pushes against the brake pads and forces one or more brake pistons into retracted positions. When the vehicle exits the turn, if the brake pistons remain in retracted positions, then they will require additional brake pedal engagement the next time the driver engages the brakes. The additional brake pedal engagement or pedal travel can be noticeable and undesirable to the driver.
One approach for addressing brake knockback is to design vehicle wheel assemblies, particularly the hubs and related components, that are oversized and thus stiffer. Although, larger and stiffer wheel assemblies can sometimes reduce the angular deflection of the rotor, such components can be more costly to manufacture and heavier on the vehicle. This can be of particular concern when they are used on high-performance vehicles.